Of note is this pic of the arcade version's character select screen that Yoshizo715 posted:

See the two blank character slots on the right and left?

Yoshizo715 wrote that he wasn't able to move the cursor to the new slots so he couldn't confirm if they're for new characters.

According to Yoshizo715, the Hey arcade has two sets of versus arcade units and one solo play unit set up. The single player version allowed for play against five characters. There were about 13 people waiting to play when Yoshizo715 arrived at Akihabara at 11:00 today.

If you're interested in participating in the location test for yourself, see this story for a schedule.